Generation, Transmission and Distribution of Electricity

Generation: it is very well known that the electrical energy is generated by a generator. The mechanical equipment driving the generator is called prime-mover. the prime mover gets its energy from the various sources. these sources of energy may be classified a follows.
(a) Primary sources like sun,wind and tide.
(b)  Secondary sources like coal, fuel oil, fuel gases, water and atomic fusion.

(a) Primary Sources: are nit used in India, become sun and wind energy will be useful only at such places where the weather remains clear for considerable duration of year.

(b) Secondary Sources: With these sources the power situation can be divided into six types
1. Diesel Power Stations
2. Steam  Power Stations
3. Coal Power Stations
4. Rice Straw fired thermal Power Stations
5. Hydro-electric Power Stations
6. Nuclear Power Stations

1. Diesel Power Stations: Where the demand of power is less, this type of Power Stations are common. the chief advantages of the IC engine plants are.

• Quick starting of the set, so that power is available at a moments notice.
• Installation cost is low.
• Occupies lesser space.

Diesel sets are mainly as standby or emergency plants in conjugation with steam station or at big companies in conjuration with the main supply. generator voltage  of such sets are usually 540 V to 600 V.

2. Steam  Power Stations: When coal is burnt, its heat energy is used to generate steam  which is generated at suitable temperature and pressure in a boiler. these are several types of boilers, but in a power station normally water tube boiler are used. the steam is used to drive a steam engine or turbine, but engine being not so economical. all modern power station have steam turbines. steam turbine drive the generators, which are normally alternating current generators. 

The alternators generate the electrical energy at 11 kV which is generally the voltage for generation. there are of course alternators which generate of 3.2 kV or 6.6 kV.

3. From Coal to electricity: Coal received from collieries in the rail wagons is mechanically unloaded  wagon tippler and carried by belt Conveyor system (1) to boiler raw coal bunkers,(2) after crushing coal crushers, the raw coal feeder regulates the quantity of coal from coal bunkers to the coal mail,(3) where coal is pulverised to a fine powder. the pulverised coal is then pushed by steam of hot air heated in air heater, (4) driven by primary air fan, (5) to boiler burners, (6) the coal being in pulveried state gets burnt immediately in the boiler furnace, (7) which comprises of water tube walls all around through which water circulates. the water gets converted into steam by the heat released by the combustion of fuel in furnace. the air required for combustion of coal is supplied by forced draft fan, (8) the products of combustion in the furnace are the flue gases and the ash. about 20% of the ash falls in the bottom ash hoppers, (9) and is further disposed off in the ash disposal area. the cleaner flue gases are off to atmosphere by the induced draft, (10) through the chimney, (11) the steam is further heated in the superheaters (12) the superheated steam at temperature of 540 Celsius is then led to the turbine Comprising of three cylinders. energy of this steam is utilised in turbine for rotating its shaft. the steam discharged from H.P. turbine. (13) is re returned to boiler reheaters, (14) for heating it once again before passing into the I.P turbine (15) the steam is then led to L.P. turbine, (16) coupled to the turbine is the generator , (17) which produces electricity when excitation current is given to its rotor through D.C. source, (18) the power from the generator is pumped into power Grid system through Generator Transformer, (19) by stepping up the voltage from 15.75 kV to 220 kV.

the steam after doing the useful work in the turbine is condensed to water in the condenser, (20) for recycling in the boiler. the cold water to the inlet of the condenser is taken from the upstream of the canal and hot water thrown back into the down stream.

the de-mineralised water called as condensate collected in the hot well of the condenser is again taken to boiler with the help of feed pump, (21) through the Economiser, (22) and boiler drum.

4. Rice Straw Fired Thermal Power Project: a new type of power generating station (10 MW)

has been set up in jalkheri village, Dist. Patiala (Punjab) in which rise straw is used as a fuel. this will lead to saving in the cost of fuel oil which is necessary for coal-fired plants besides reduction in maintenance costs due to absence of coal handling and coal milling plants.

5. Hydro-electric power station: bhakra nangal project is an example of hydro-electric power stations. other example are chambal project which is a joint venture of Rajasthan and Madhay pradesh states, Kota Dam, Rihand, Koyna, B.V.D, etc.

Advantages of hydro-electric power station:

1. the running charges of stations are very small.

2. the coal and oil thus saved can be better utilized in the country.

3. plat is simpler and maintenance is minimum.

4. Losses are less (standby).

Generally, the generated voltage is at 11 kV or 33 kV and the transmission voltage 66 kV, 132 kV or sometime 220 kV. the main transformer and main switch gear is of outdoor type and all the other equipment is of indoor type, i.e.,  located inside the building.

6. Nuclear Power Station: in our country 380 MW Nuclear power station at Tarapur  is working and electrical energy on commercial is available from  this station. another nuclear power station of 400 MW is also working near rana pratap sagar (Rajasthan).

 What is it ?: the reserves mineral fuels in the world are limited, and as result of the rapid growth of their industrial exploitation they will become exhausted in not too distant future so it is natural to look for new sources of power.

the energy of atomic nucleus used in such system is called atomic or nuclear, since it is heat energy, obtained during the fission of heavy atomic nuclei. A neutron hits nucleus and splits in into two approximately equal halves, releasing at the some time several neutrons and beta and gamma remediation. to obtain this energy continuously atomic reactors are used.

A nuclear power station is just like a thermal power station in which the nuclear reactor replaces the steam boiler. here to obtain 100000 kW of heat it is enough to burn only 100 grams of nuclear material daily. but control of this "Burning" is a very complex problem.